TeleGPS Battery Life

I charged up one of the
"160mAh" batteries that we sell.
(The ones we've got now are labeled 200mAh; the 160mAh rating is
something like a minimum that we expect to be able to ever get at that size.)

I connected the battery to a TeleGPS board, hooked up a telemetry monitoring
setup on my laptop and set the device in the window of my office. This
let me watch the battery voltage through the day without interrupting
my other work. Of course, because the telemetry was logged to a file,
I've now got a complete plot of the voltage data:

It looks like a pretty typical lithium polymer discharge graph;
slightly faster drop from the 4.1V full charge voltage down to about
3.9V, then a gradual drop to 3.65 at which point it starts to dive as
the battery is nearly discharged.

Because we run the electronics at 3.3V, and the LDO has a dropout of
about 100mV, it's best if the battery stays above 3.4V. That occurred
at around 21500 seconds of run time, or almost exactly six hours.

We also have an
"850mAh" battery
in the shop; I'd expect that to last a bit more than four times as
long, or about a day. Maybe I'll get bored enough at some point to
hook one up and verify that guess.